Wall Street set for a weak open as investors digest tax plan developments By: CNBC.com News December 21, 2017 at 05:21 AM EST U.S. stock index futures are pointing to a mixed open on Thursday, after a major bill was approved by Congress. Read More >> Related Stocks: Dow Industrials SPDR PowerShares QQQ S&P 500 Ishares Core ETF S&P Depository Receipts